The modern internal combustion engine usually incorporates a pulley drive system for powering accessories driven by the engine crankshaft. The accessories typically include an air conditioning compressor, a power steering pump, a water pump, and an alternator. A front end accessory drive belt is trained around pulleys to supply power from the crankshaft of the engine to the accessories. The drive belt makes frictional contact with the face of the pulleys. The drive belt is most often a flexible reinforced polymeric belt.
Each of the accessories requires a driven pulley. In addition, operating a number of accessories, particularly with a serpentine drive belt, requires that the belt be handled carefully to allow placement of the belt in the locations needed to drive the accessories without slippage. It is necessary to maintain the proper tension in this belt, thus ensuring both prevention of slip at the accessory pulleys or at the crankshaft pulley and long life for the belt.
A variety of arrangements are known for establishing and maintaining the desired tension on the belt. The most common arrangement is the front end accessory drive automatic belt tensioner that includes a pivotable arm having a pulley at one end. The other end of the arm is pivotably attached to a housing that attached to the front of the engine block. The housing includes an internal clock spring that provides tension. The front end accessory drive automatic belt tensioner ensures that the belt is placed under a constant tension that is maintained regardless expansion and contraction of the belt itself and of the other engine components which can affect belt tension.
A challenge faced by the industry is that there is no known generic front end accessory drive automatic belt tensioner that adequately respond to the differences between engines. This is because front end accessory drive systems typically have unique accessory and pulley locations on the engine. The front end accessory drive automatic belt tensioner used today to provide and maintain belt tension to drive the accessories is typically unique for each engine and is designed for the specific accessories initially intended for that engine/program. Changing or adding accessories to locations from the initial design can be done, but very often this requires a new tensioner design for each arrangement in order for the system to achieve optimum functionality. The individualized tensioner results in additional cost and complexity for both manufacturing and service.
As in so many areas of vehicle technology there is always room for improvements related to the design of a pulley system for use in an internal combustion engine. Particularly, it would be advantageous to provide a tensioning system in which proper belt tension is constantly applied to the belt system of a given drive and accessory arrangement.